1. Field of the Invention
This invention pertains to a piston pump useful for operating in an environment of slush or slurry and more specifically to such a single-acting piston pump utilizing two heads each in sealing engagement and operation with the inside bore of the chamber or cylinder of the pump.
2. Description of the Prior Art
Slushes and slurry, such as in an oil well bore application or in a coal pipe line application, include extremely abrasive materials requiring the use of an elastomeric seal at the piston head. Even so, such abrasiveness quickly wears out piston pump seal parts and cylinders that operate in conjunction therewith.
Moreover, such pumps commonly work in environments commonly in excess of 1000 psi. Hence, for a piston pump seal parts that may last 2000-3000 hours at a few hundred psi, such parts last only between 500-1000 hours when operated at 3500 psi, all other conditions remaining the same. In addition, it is known that pump piston seals and cylinders have a longer life, even at high pressures, if the fluid with which they operate is lubricous and free of abrasive particles.
In brief, the seals and bores of cylinders on a piston wear out quickly when (1) the fluid is abrasive or of low lubricity, and (2) the operating conditions are at high pressure. Life of the seal parts is extendable, therefore, by making cleaner or more lubricous the fluid in which high operating pressure occurs and/or by reducing the operating pressure in which the movable seal parts operate.
Prior art piston pumps have focused on improving the seal material, establishing duplex and even triplex operation of the parts to reduce the wear on the sealing parts. Prior art solution attempts have been expensive and/or more complex than the solution to the above problems solved by the embodiments of the present invention.
Therefore, it is a feature of the present invention to provide an improved piston pump providing a more clean and lubricous environment for one of the chief operating high pressure seal parts than provided in the prior art.
It is another feature of the present invention to provide an improved piston pump which provides a reduced pressure environment for another of the chief operating seal part, which part is subjected to the abrasive slush in the piston chamber.